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Warranted Wiretapping: Listening in on Cancer’s Conversations

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Science Translational Medicine  12 Dec 2012:
Vol. 4, Issue 164, pp. 164ec224
DOI: 10.1126/scitranslmed.3005442

Sometimes it seems like we can no longer go a day without sending a message by e-mail, Twitter, or SMS. Connectivity is just as important to cancer cells. Microvesicles—small , secreted lipid vesicles that can contain a variety of signaling proteins, receptors, and microRNA—can be produced by virtually all cell types, but cancer cells make them in large quantities. Although the role of microvesicles in cancer biology, also known as exosomes, is not completely understood, they provide a means for cells to communicate by sending “packets” of signaling molecules and gene regulatory microRNA that can be “downloaded” by other cells. Cancers of the brain are notoriously difficult to monitor, requiring imaging and/or direct tissue biopsy for diagnosis or to determine whether treatment is working. In a recent study, Shao et al. have developed a microfluidic chip-based assay that can detect the microvesicles in the blood and provide a means to detect and track brain cancer.

Shao and colleagues created a microfluidic chip that separates microvesicles by size and by immunoaffinity for a marker specific to microvesicles. The isolated microvesicles were then labeled with magnetic nanoparticles by using a two-step process. A critical innovation in their device was the use of a tiny coil in the microfluidic chip to perform micro-nuclear magnetic resonance to detect the labeled microvesicles. When compared with the current techniques for detecting microvesicles, the authors found their labeling/detection system to be around 1000 times more sensitive then the most sensitive current available method. The researchers then profiled the microvesicles from the blood of healthy patients and those with glioblastoma (GBM). By examining four markers found in the patients’ microvesicles, they devised an assay with greater than 90% accuracy for the detection of GBM. In addition, they analyzed the changes in the circulating microvesicles in mice injected with human tumors and in human patients undergoing chemotherapy for GBM. Their detection system was able to predict which patients/tumors would respond to chemotherapy.

The work of Shao et al. demonstrates the creation and testing of technology to allow the measurement of microvesicles in the blood. Their work is particularly powerful in terms of translational potential in that they have shown the ability to detect cancer and predict aspects of chemotherapeutic response in human patients. In a broader view, microvesicle analysis may provide key insights into the progression and treatment of many diseases and thus provide further applications for their technology.

H. Shao et al., Protein typing of circulating microvesicles allows real-time monitoring of glioblastoma therapy. Nat. Med., published online 11 November 2012 (10.1038/nm.2994). [PubMed]

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